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It sure will. This article explains when and how:

https://www.gardeningknowhow.com/ornamental/flowers/coreopsis/growing-coreopsis-flowers.htm

Do not cut them all the way back. Leave 6 to 8 inches of stem to help protect the crown in the winter.

Make your pruning cuts at a node on the stem.

You can individually remove the spent flowers with small garden scissors or cut the entire plant down by 1/3 after flowering.

https://www.gardeningknowhow.com/ornamental/flowers/coreopsis/growing-coreopsis-flowers.htm

Check the soil; it should be moist, never soggy or dry.
Make sure the soil and the container have a drainage hole and that the excess water is draining.
You may need to water daily, and even twice a day if the temperatures are above 85 degrees F.

https://www.gardeningknowhow.com/ornamental/flowers/coreopsis/growing-coreopsis-flowers.htm

It is best to wait until the plant is done flowering.

Only go up one size in pots to avoid overwatering and root rot.

Expect transplant shock, especially in mid-summer. The plants were probably left over from spring so were rootbound and not in good shape, as you said. Roots are now struggling to get established. Blooms take a lot out of a plant energy wise and are the first thing to suffer in transplants. I would actually trim back the entire plant to get rid of buds. Let it focus on roots, then green growth, then flowers. Coreopsis doesn't like a lot of water or fertilizer. Is this in a pot? Only water when the top 1" of soil is dry. Your goal is damp, not wet, soil. Provide shade for the rest of this week; hot sun will dry the leaves and blooms faster than the roots can replace water. Unlike annuals, perennials often don't show much top growth their first year.